Dobby for looms

ABSTRACT

A high-speed dobby with heddles which are moved in one direction by means of a springs and in the opposite direction by means of a cam and lever assembly.

United States Patent [72] Inventors Giovanni Pianolla Carlo Vill a, ViaMazzini, 43, Melzo, both Via Salieri 6, Milan;

0!, Italy Appl. No. 804,454 Filed Mar. 5, 1969 Patented Sept. 7, 1971Priority Mar. 6, 1968 Italy DOBBY FOR LOOMS 7 Claims, 2 Drawing Figs.

IU.S. C11

Int. Cl

Field of Search 139/70, 139/57 D03c 5/00, D03C13/O0 References CitedUNITED STATES PATENTS Draper Cosman Firing et a1 Herard, Jr. et a1..Iuillard FOREIGN PATENTS 7/1964 Canada Great Britain PrimaryExaminer-James Kee Chi Anorney-Michae1 S. Striker ABSTRACT: A high-speeddobby with heddles which are moved in one direction by means of asprings and in the opposite direction by means of a cam and leverassembly.

PATENTEDSEP Han 3503351 SHEET 1 OF 2 y ammo V1644 DOBBY FOR LO-OMSBACKGROUND OF THE INVENTION This invention relates to looms, inparticular dobby looms.

Small looms for the production of ribbon fabrics comprising small unitsequipped with a few wefting devices arranged side by side for theparallel production of ribbon fabrics are known to those skilled in theart. Small looms are preferred because they can be operated at highspeeds, for example, 1,000 to L500 beats per minute. It has not beenpossible to increase the operating speed of small looms beyond 1,500beats per minute. This is attributable to the fact that the dobbyheddles are moved in two directions by means of grooved cylinder camscooperating with rollers which impart motion through articulated levers.The action of the articulated levers through the clearance betweenrollers and cam grooves causes flopping of the levers, noise, and acorresponding surface wear on the cams, thus limiting the operatingspeed of the dobby and requiring replacement of moving parts after shortperiods of operation.

SUMMARY OF THE INVENTION It is an object of this invention to overcomethe speed limitation present in a conventional dobby loom through theuse of simple easily installed mechanisms.

Another object of the invention is to reduce the frequency ofreplacement of certain movable parts in a dobby loom.

Another object of the invention is to reduce the surface wear of cams indobby looms and thereby increase their useful life.

Another object of the invention is to reduce the noise now present in adobby loom.

Another object is to simplify the operations required to modify orchange a fabric pattern produced by a dobby loom.

Another object is to provide a motion transmission member which can beadjusted to compensate for wear or for varying initial positions ofheddles.

The invention resides in the provision of a loom, particularly a dobbyloom, which comprises a plurality of movable heddles, guide means forrestricting the heddles to reciprocatory motion, and drive means forreciprocating the heddles. The drive means comprises a biasing means foryieldably urging the heddles in one direction, and positive displacementmeans for intermittently moving the heddles in the opposite directionagainst the resistance of the biasing means.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved apparatus itself, however, both as to its construction and itsmode of operation, together with additional features and advantagesthereof, will be best understood upon perusal of the following detaileddescription of certain specific embodiments with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional viewof a small loom with certain parts shown in elevation into which anembodiment of the invention has been incorporated; and

FIG. 2 is an enlarged sectional view as seen along line II-II of FIG.ll.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the drawings,FIG. 1 shows a small loom for the fabrication of ribbon fabricscomprising a frame 1, equipped with a pair of weaving devices 2 and aweft beating reed 3. A pack of heddles 4 behind reed 3 moves warp 5.

The heddles 4 are supported and guided by motion-transmitting rods, twoof which are shown at 6 and 6'. The lower ends of the rods are connectedto biasing means here shown as including pairs of helical expansionsprings 7and 8. The lower ends of the springs are anchored in a retainer34 which is ad justable in either of the directions indicated by thedoubleheaded arrow in FIG. 1 to thereby select the initial spring bias.Helical expansion springs 7'and 8 are so located that they provide atlast a component of the bias axially directed as the correspondingrods 6or 6'.

The rods are adjustable as shown at6a, in order to vary the initialpositions of heddles 4, or to compensate for wear on the movable parts,herein later described in detail. Rods 6 and 6 have seats 9 fitted abouttheir midportion, onto which lightweight follower rollers 10 of smalldiameter are fitted;

A set of bent-levers 12, one for each rod, is rotatable around. a pivot11. Each lever 12 has an arm 13 at the end of which a follower roller 14contacts the external profile of a cam 15. the contact pressure being afunction of the bias provided by springs 7 and 8. At the other end ofeach lever l2a flattened arm 16 or 16 contacts a roller 10 on rod 6 or6. The lengthof arms 16 and 16 is dependent upon the distance of rods 6and 6' from the pivot 11; thus arm 16 which contacts roller 10 on rod 6is shorter than arm 16' which extends to rod 6. A constant contactpressure between rollers 10 and the ends of arms 16 and 16' ismaintained by the bias of springs 7 and 8. As shown in FIG. 1, motion istransmitted from the earns 15 by means of the levers 12 to rods 6 and6'. Interposed between these elements are rollers 14 and 10 whichcontact the corresponding cam 15 and arms 16 and 16' respectively. Thecontact pressure of these rollers against their respective contactelements remains constant because of the bias of springs 7 and 8,thereby eliminating clearances between the rollers and their contactelements. Thus impact, shock or vibration which might affect the motionof rods 6 and 6' is reduced, thereby lessening the wear on the operatingand contact elements. In addition, the noise of the operating elementsis also reduced.

Cams l5, levers l2 and those portions of the rods which support rollers10 are enclosed by an oil-bath housing 17.

Rods 6 and 6' are guided in housing 17 by means of sealing rings 18 and19 which are mounted in the upper and lower walls of the housing. I

As shown in FIG. 2, earns 15 are assembled on an internal sleeve 21which is mounted on shaft 20. Sleeve 21 has a flange 22 which permitstightening of the stack of cams by means of screws 23 against a secondflange 24 which is fixed to the shaft 20.

Sleeve 21 is secured to shaft 20 at one end by means of one or more keys25.

Shaft 20 is supported at its ends by means of supports 26 and 27 withinterposed ball or roller bearings 26' and 27 respectively.

Transmission of motion from an external prime mover (not shown) to shaft20 is by means of a gear 28 which meshes with a toothed belt 29. Aninternally fluted hub 30 on gear 28 receives the externally splined end31 of shaft 20 in such a manner that the shaft can be driven out axiallyand removed from its housing 17.

Support 26 is secured to the lateral sides 33 of housing 17 by means ofscrews 32. When it is desired to change the fabric pattern, thelubricant is drained from housing 17 and screws 32 are removed from thesides 33 of the housing. After removing the support 26, shaft 20 withits stack of cams can be withdrawn. Another shaft with cams of adifferent external profile can then be rapidly installed, and a newfabric pattern can be produced.

The same result can be achieved if the stack of earns 15 on shaft 20 isreplaced with cams of a different external profile.

The improved apparatus is susceptible of many modifications withoutdeparting from the spirit of this invention. For example, each rod 6 or6' can be biased by a single spring. It is also possible to employ othertypes of wefting devices and/or other fastening means for the cams. Itis further possible to use other types of biasing means in addition to,or as a substitute for springs 7 and 8.

Without further analysis, the foregoing will so fully reveal the gist ofthe present'invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of the above-described contribution to the art.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended: H

1. In a loom, particularly a dobby loom, in combination, a plurality ofmovable elongated heddles; guide means for guiding said heddles forreciprocating movement in longitudinal direction and comprising ahousing and a plurality of motiontransmitting rods respectively axiallyaligned with and connected to said heddles and being reciprocally guidedin said housing; and drive means cooperating with saidmotion-transmitting rods for reciprocating the latter and the heddlesconnected thereto, said drive means comprising biassing means foryieldably urging said rods in one direction and positive displacementmeans comprising follower means mounted on said rods, rotary cam meansand means for transmitting motion from said cam means to said followermeans for intermittently moving said follower means in the oppositedirection against the resistance of said biassing means.

2. A structure as defined in claim 1, wherein said cam means comprises aplurality of relatively discrete cams. I

3. A structure as defined in claim 1, wherein said positive displacementmeans further comprises a rotary support for said cam means and meansfor separably connecting said cam means to said support.

4. A structure as defined in claim l, wherein said means fortransmitting motion from said cam means to said follower means compriseslever means pivotable about a single predetermined axis, said levermeans having first arm means engaging said follower means, and secondarm means provided with second follower means tracking said cam means.

5. A structure as defined in claim 1, wherein said biasing meanscomprises a plurality of spring means.

6. A structure as defined in claim 5, wherein said spring means arehelical expansion springs.

7. A structure as defined in claim 1, wherein said housing at leastpartially encloses said positive displacement means and furthercomprising a supply of lubricant in said housing.

1. In a loom, particularly a dobby loom, in combination, a plurality ofmovable elongated heddles; guide means for guiding said heddles forreciprocating movement in longitudinal direction and comprising ahousing and a plurality of motion-transmitting rods respectively axiallyaligned with and connected to said heddles and being reciprocally guidedin said housing; and drive means cooperating with saidmotion-transmitting rods for reciprocating the latter and the heddlesconnected thereto, said drive means comprising biassing means foryieldably urging said rods in one direction and positive displacementmeans comprising follower means mounted on said rods, rotary cam meansand means for transmitting motion from said cam means to said followermeans for intermittently moving said follower means in the oppositedirection against the resistance of said biassing means.
 2. A structureas defined in claim 1, wherein said cam means comprises a plurality ofrelatively discrete cams.
 3. A structure as defined in claim 1, whereinsaid positive displacement means further comprises a rotary support forsaid cam means and means for separably connecting said cam means to saidsupport.
 4. A structure as defined in claim 1, wherein said means fortransmitting motion from said cam means to said follower means compriseslever means pivotable about a single predetermined axis, said levermeans having first arm means engaging said follower means, and secondarm means provided with second follower means tracking said cam means.5. A structure as defined in claim 1, wherein said biasing meanscomprises a plurality of spring means.
 6. A structure as defined inclaim 5, wherein said spring means are helical expansion springs.
 7. Astructure as defined in claim 1, wherein said housing at least partiallyencloses said positive displacement means and further comprising asupply of lubricant in said housing.
 2. A structure as defined in claim1, wherein said cam means comprises a plurality of relatively discretecams.
 3. A structure as defined in claim 1, wherein said positivedisplacement means further comprises a rotary support for said cam meansand means for separably connecting said cam means to said support.
 4. Astructure as defined in claim 1, wherein said means for transmittingmotion from said cam means to said follower means comprises lever meanspivotable about a single predetermined axis, said lever means havingfirst arm means engaging said follower means, and second arm meansprovided with second follower means tracking said cam means.
 5. Astructure as defined in claim 1, wherein said biasing means comprises aplurality of spring means.
 6. A structure as defined in claim 5, whereinsaid spring means are helical expansion springs.
 7. A structure asdefined in claim 1, wherein said housing at least partially enclosessaid positive displacement means and further comprising a supply oflubricant in said housing.